More particularly, the invention relates to a manual spraying device comprising:                a push-button that can be actuated manually, said push-button comprising a spray nozzle, said spray nozzle having an inner chamber adapted to receive a non-gaseous fluid product under pressure and delimited towards the outside by a perforated front wall,        a reservoir for the fluid product to be sprayed,        and a dispensing device that can be mechanically actuated by the push-button and adapted to transfer the fluid product from the reservoir to the inner chamber of the nozzle.        
Document U.S. Pat. No. 6,145,712 describes an example of such a spraying device, wherein the front face of the spray nozzle has a single central hole.
In spraying devices of this type, the spray nozzles, which are conventionally mounted on pumps or on spray valves, have the disadvantage of bringing about a large dispersion of the diameter of the droplets of the sprayed fluid product.
Indeed, in spray nozzles of a device of this type, the fluid product is split up into fine droplets by a dynamic phenomenon that is particularly difficult to control, generally consisting of creating a vortex inside the inner chamber of the nozzle and of splitting up the fluid product into fine droplets as it leaves at a very high velocity through the central hole.
As an example, it has been possible to measure that, for a spray nozzle of the aforementioned type, of which the inner chamber receives an alcoholic solution under a pressure of 5 bar from a manual pump or a valve, and for a central hole of the nozzle having a diameter of 0.3 mm, the sprayed product consists of droplets having diameters of between 5 μm and 300 μm.
This dispersion can prove to be undesirable when it is desired to spray droplets with substantially uniform sizes. For example, it may be desired to spray droplets with a small size for the inhalation of medicinal treatments of the bronchi, or furthermore, it may be desired to spray larger droplets for cosmetic or perfumery applications, so that the droplets penetrate as little as possible into the bronchi of the user.
Moreover, droplets with very different sizes also follow very different trajectories, which is harm for the controlled application of the sprayed product. For example, when spraying a perfume onto the skin of a user, droplets that are too large can fall on the clothes of the user instead of being projected onto the skin, with the risk of producing indelible spots.